Image processing apparatus with improved image processing efficiency

ABSTRACT

A multifunctional printer comprises a CCD for reading an image on one side of a document, a CIS for reading an image on the other side of the document, an image processing unit for processing the image of the side read by the CCD or the CIS, and a determining unit (S 12 ) for determining which of the images of the sides read by the CCD and the CIS is to be processed first by the image processing unit.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to an image processingapparatus. More particularly, the present invention relates to an imageprocessing apparatus capable of simultaneously reading both sides of adocument.

2. Description of the Background Art

There are image processing apparatuses which have two reading portionsfor respectively reading both sides of a document (that is, front andback sides of a document) so that images on both sides of the documentcan be simultaneously read by one-time feeding without reversing thedocument. For example, a CCD (Charge Coupled Device) for reading animage on a front side of a document and a CIS (Contact Image Sensor) forreading an image on a back side of a document are provided on atransport path of a document feeder, and the CCD and the CIS read imageson both sides of a document. Since there is no need to reverse adocument, this structure reduces the time required to read images onboth sides of a document, thereby implementing reduction in overallimage processing speed.

A technology regarding an image processing apparatus capable of readingimages on both sides of a document is disclosed in Japanese PatentPublication No. 2002-232671 of unexamined applications. According tothis publication, image data read from both sides of the document istransmitted to the outside in an optimal order according to thetransmission rate of the image data to the outside.

According to this publication, the data can be transmitted to theoutside in an optimal order according to the transmission rate. Eventhough the order of transmitting the data is optimal according to thetransmission rate to the outside, however, the order may not be optimalin the overall system of the image processing apparatus. Therefore, theimage processing efficiency may not be appropriate.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an image processingapparatus with improved image processing efficiency.

It is another object of the present invention to provide an imageprocessing method with improved image processing efficiency.

An image processing apparatus according to one aspect of the presentinvention is capable of reading images on both sides of a document whiletransporting the document. The image processing apparatus comprises: afirst image reading unit for reading an image on one side of thedocument; a second image reading unit for reading an image on the otherside of the document; an image processing unit for processing the imagesof the side read by the first and second image reading unit; and adetermining unit for determining which of the images of the sides readby the first and second image reading units is to be processed first bythe image processing unit.

According to the present invention, of the images on both sides of thedocument read by the first and second image reading units, the image ofthe side to be processed first by the image processing unit isdetermined. This can improve the image processing efficiency as theoverall system of the image processing apparatus. For example, in thecase where a reading unit for reading the front side of the document anda reading unit for reading the back side of the document are provided atdifferent positions in the image processing apparatus, the image on theside that was read first can be processed first. The image processingefficiency can thus be improved.

Preferably, the determining unit determines that the image of the sidethat was read first by the first or second image reading unit is to beprocessed first.

The determining unit may determine that the image of the side thatrequires a shorter image processing time of the image processing unit isto be processed first.

The image processing apparatus may further include a selecting unit forallowing selection about which of the images of the sides read by thefirst and second image reading units is to be processed first, and thedetermining unit may determine that the image of the side selected bythe selecting unit is to be processed first.

More preferably, the image processing unit performs image processing ona page-by-page basis.

An image processing method according to another aspect of the presentinvention is an image processing method for reading images on both sidesof a document while transporting the document, and processing the readimages. The image processing method includes the steps of; reading animage on one side of the document; reading an image on the other side ofthe document; determining which of the images of the sides is to beprocessed first; and processing the image of the determined side first.Such an image processing method can improve the image processingefficiency.

Preferably, in the image processing method, it is determined that, ofthe read images on both sides of the document, the image of the sidethat was read first is to be processed first.

In the image processing method, it may be determined that, of the readimages on both sides of the document, the image of the side thatrequires a shorter image processing time is to be processed first.

In the image processing method, it may be determined that, of the readimages on both sides of the document, the image of the side selected tobe processed first is to be processed first.

In a more preferred embodiment, in the image processing method, imageprocessing is performed on a page-by-page basis. More preferably, in theimage processing method, an image on one side of a document is read by aCCD for reading an image on a document by emitting light to the documentand receiving reflected light from the document.

In the image processing method, an image on the other side of a documentmay be read by a CIS for reading an image on a document by emittinglight to the document from a built-in light source and receivingreflected light from the document.

In the image processing method, an image on one side of a document maybe read by a CCD for reading an image on a document by emitting light tothe document and receiving reflected light from the document, an imageon the other side of the document may be read by a CIS for reading animage on a document by emitting light to the document from a built-inlight source and receiving reflected light from the document, and it maydetermined that the image on the side read by the CIS is to be processedfirst.

In the image processing method, image processing may be performed on aline-by-line basis in a page.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the overall structure of amultifunctional printer according to an embodiment of the presentinvention;

FIG. 2 is a schematic diagram showing an original feeding device and animage reading unit which are included in the multifunctional printer;

FIG. 3 is a flowchart illustrating an operation of a controller in imageprocessing; and

FIG. 4 is a diagram showing an example of an operation panel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention will be describedwith reference to the accompanying drawings. FIG. 1 is a block diagramshowing a structure of a multifunctional printer 10. In this example, animage processing apparatus according to an embodiment of the presentinvention is applied to the multifunctional printer 10. Referring toFIG. 1, the multifunctional printer 10 comprises a controller 11, a DRAM(Dynamic Random Access Memory) 12, an operation unit 13, a originalfeeding device 14, an image reading unit 15, an image forming unit 16, ahard disk 17, a FAX communication unit 18, and a network IF (interface)unit 19. The controller 11 generally controls the multifunctionalprinter 10. The DRAM 12 performs write and read operations of data suchas image data. The operation unit 13 includes a display screen fordisplaying information that the multifunctional printer 10 has, andserves as an interface between the multifunctional printer 10 and theuser. The original feeding device 14 automatically transports a documentto a predetermined document read position. The image reading unit 15reads an image of the document transported by the original feedingdevice 14 at the predetermined read position. The image forming unit 16forms an image based on the document or the like read by the imagereading unit 15 and outputs the image onto paper or the like. The harddisk 17 stores image data or the like therein. The FAX communicationunit 18 is connected to a telephone line 20. The network IF unit 19 isconnected to a network 21. The original feeding device 10 furtherincludes an image processing unit for processing an image that is readby the image reading unit 15.

The controller 11 compresses and encodes document data received from theimage reading unit 15 and writes the resultant data to the DRAM 12. Thecontroller 11 also reads the data from the DRAM 12, decompresses andencodes the read data, and outputs the resultant data from the imageforming unit 16.

The multifunctional printer 10 operates as a copying machine by formingan image in the image forming unit 16 through the DRAM 12 by using adocument read by the image reading unit 15. The multifunctional printer10 also operates as a printer by forming an image in the image formingunit 16 through the DRAM 12 by using image data received from a personalcomputer (PC) 22 connected to the network 21 through the network IF unit19. The multifunctional printer 10 also operates as a facsimile machineby forming an image in the image forming unit 16 through the DRAM 12 byusing image data received from the telephone line 20 through the FAXcommunication unit 18, or by transmitting image data of a document readby the image reading unit 15 to the telephone line 20 through the FAXcommunication unit 18.

Note that, in FIG. 1, thick arrows indicate a flow of image data, andthin arrows indicate a flow of a control signal or control data.

A specific structure of the original feeding device 14 and the imagereading unit 15 will now be described. FIG. 2 is a schematic diagramshowing a part of the original feeding device 14 and the image readingunit 15. Referring to FIGS. 1 and 2, the image reading unit 15 includesa CCD 31 as a first reading unit for reading image data of one side(front side) of a document, and a CIS 32 as a second reading unit forreading image data of the other side (back side) of the document. Theoriginal feeding device 14 includes a transporting member fortransporting a document. A document is transported by the transportingmember in the direction shown by arrow in FIG. 2. Note that the side towhich a document is transported is herein referred to as a “downstream”side.

The transporting member includes a pickup roller 33, a separating roller34, transporting rollers 35, 36, 37 a, 37 b, a discharging roller 38,and a guide member 39. The pickup roller 33 sequentially feeds documentsthat are placed and set on a tray 41. The separating roller 34 separatesthe documents one by one. The transporting rollers 35, 36, 37 a, 37 btransport a document to the CIS 32 and the CCD 31. The dischargingroller 38 discharges a read document. The guide member 39 guides adocument transported by the feeding rollers 37 a, 37 b to the CCD 31.

The CIS 32 includes a built-in light source (not shown). The CIS 32reads image data of the back side of a document by emitting light to theback side of the document from the built-in light source and receivingreflected light from the document. The CCD 31 reads image data of thefront side of a document by emitting light to the front side of thedocument through a read glass 40 from a light source 42 and receivingreflected light from the document.

The CIS 32 is provided between the transporting roller 36 and thetransporting rollers 37 a, 37 b. The CCD 31 is provided downstream ofthe transporting rollers 37 a, 37 b and under the read glass 40. Inother words, the CIS 32 is provided upstream of the CCD 31. Since theCCD 31 and the CIS 32 are thus provided at different positions, problemssuch as see-through of an image of a document caused by reflected lightare prevented, and an image on each side of a document is readappropriately.

An example in which images on both sides of a document are read andformed by the multifunctional printer 10 will now be described. FIG. 3is a flowchart illustrating an operation of the controller in thisexample. Referring to FIGS. 1 through 3, a document is first placed onthe tray 41. In response to a command to copy images on both sides of adocument, the controller 11 transports the document by the originalfeeding device 14 and starts reading images on both sides of thedocument by the CIS 32 and the CCD 31 (Step S11 in FIG. 3; hereinafter,the word “Step” will be omitted). More specifically, an image on theback side of the document is read by the CIS 32 and an image on thefront side of the document is read by the CCD 31.

Next, the side of the document which was read first is determined (S12).In this case, since the CIS 32 is located upstream of the CCD 31, it isdetermined that the back side read by the CIS 32 was read first (YES inS12). In this case, the controller 11 operates as a determining unit.Processing of the image of the back side is thus started first (S13). Inthis case, the image processing is performed on a page⁻by-page basis.Processing of the image of the front side is performed after the imageprocessing of the back side is completed.

In this way, the controller 11 determines that the image of the sidethat was read first by the CCD 31 or the CIS 32 is to be processedfirst. In this case, since the image of the back side is first read bythe CIS 32, image processing of the back side can be performed as soonas reading of the image of the back side is started. In the case wherethe image processing of the back side is completed during reading of theimage of the front side by the CCD 31, image processing of the frontside can be started even during reading of the front side. Therefore,for example, the time to make a first copy can be reduced, whereby theimage processing efficiency can be improved.

Hereinafter, an example in which a CIS 43 is provided downstream of theCCD 31 as shown by dotted line in FIG. 2 will be described. In thiscase, it is determined that the front side read by the CCD 31 was readfirst (NO in S12). Image processing of the front side is thus startedfirst. Image processing of the back side is performed after the imageprocessing of the front side is completed. The image processingefficiency can thus be improved.

Note that, in the above embodiment, it is determined that an image ofthe side that was read first is to be processed first. However, thepresent invention is not limited to this. After images on both sides ofa document are read, the image of the side that requires a shorter imageprocessing time may be determined and image processing of the determinedside may be performed first. For example, if an image is to be formed atdifferent scale factors between the front side and back side of adocument, a region to be read (a read region) is different between thefront side and back side of the document. In the case where theprocessing time is proportional to the area of the read region, that is,in the case where the processing time decreases with decrease in thearea of the read region, an image of the side having a smaller readregion is processed first. This method can also improve the imageprocessing efficiency. In this case, the present invention is alsoapplicable to a multifunctional printer in which a CCD and a CIS areprovided at the same position in a transport path, that is, amultifunctional printer in which a CIS is provided above a CCD.

In the multifunctional printer, an operation panel for allowingselection of the side to be processed first may be displayed on adisplay screen included in the operation unit, and the determining unitmay determine that the side selected by a user or the like through theoperation panel is to be processed first. In this case, the operationunit operates as a selecting unit. FIG. 4 shows an example of theoperation panel of this example. Referring to FIG. 4, an operation panel23 is displayed on a display screen of the operation unit 13. Theoperation panel 23 included in the operation unit 13 includes a selectbutton 24 a for selecting a front side of a document as a side to beprocessed first, and a select button 24 b for selecting a back side of adocument as a side to be processed first. According to a user's request,the user selects a side of a document to be processed first by pressingthe select button 24 a or 24 b before a document is read. It is thusdetermined that the selected side is to be processed first. In this way,for example, an image of the side that is requested to be printed firstis processed first according to the user's request. The printing speedcan thus be increased. In this case as well, the present invention isalso applicable to a multifunctional printer in which a CCD and a CISare provided at the same position in a transport path.

Note that, in the above embodiment, image processing is performed on apage-by-page basis. However, the present invention is not limited tothis. For example, image processing may be performed on a line-by-linebasis in a page.

An image processing method according to the present invention is animage processing method for reading images on both sides of a documentwhile transporting the document, and processing the read images. Theimage processing method comprises the steps of: reading an image on oneside of the document; reading an image on the other side of thedocument; determining the image of which side is to be processed first;and processing the image of the determined side first. This imageprocessing method can improve the image processing efficiency.

Preferably, in the image processing method, it is determined that, ofthe read images on both sides of the document, the image of the sidethat was read first is to be processed first.

In the image processing method, it may be determined that, of the readimages on both sides of the document, the image of the side thatrequires a shorter image processing time is to be processed first.

In the image processing method, it may be determined that, of the readimages on both sides of the document, the image of the side selected tobe processed first is to be processed first.

In a more preferred embodiment, image processing is performed on apage-by-page basis in the image processing method.

More preferably, in the image processing method, an image on one side ofa document is read by a CCD for reading an image on a document byemitting light to the document and receiving reflected light from thedocument.

In the image processing method, an image on the other side of a documentmay be read by a CIS for reading an image on a document by emittinglight to the document from a built-in light source and receivingreflected light from the document.

In the image processing method, an image on one side of a document maybe read by a CCD for reading an image on a document by emitting light tothe document and receiving reflected light from the document, an imageon the other side of the document may be read by a CIS for reading animage on a document by emitting light to the document from a built-inlight source and receiving reflected light from the document, and it maybe determined that the image on the side read by the CIS is to beprocessed first.

In the image processing method, image processing may be performed on aline-by-line basis in a page.

Although an embodiment of the present invention has been described abovewith reference to the figures, the present invention is not limited tothe above described and illustrated embodiment. Various modificationsand variations can be made to the above described and illustratedembodiment within the same scope as, or an equivalent scope to, thepresent invention.

1.-18. (canceled)
 19. An image processing apparatus capable of readingimages on both sides of a document while transporting said document,comprising: a first image reading unit for reading an image on one sideof said document; a second image reading unit for reading an image onthe other side of said document; an image processing unit for processingthe image of the side read by said first and second image reading unit;and a determining unit for determining which of the images of the sidesread by the first and second image reading units is to be processedfirst by said image processing unit, wherein said determining unitdetermines that the image of the side that requires a shorter imageprocessing time of said image processing unit is to be processed first.20. The image processing apparatus according to claim 19, wherein saidimage processing unit performs image processing on a page-by-page basis.21. The image processing apparatus according to claim 19, wherein saidfirst image reading unit includes a CCD for reading an image on a frontside of a document by emitting light to the front side of said documentand receiving reflected light from said document.
 22. The imageprocessing apparatus according to claim 19, wherein said second imagereading unit includes a CIS for reading an image on a back side of adocument by emitting light to the back side of said document from abuilt-in light source and receiving reflected light from said document.23. The image processing apparatus according to claim 19, wherein saidimage processing unit performs image processing on a line-by-line basisin a page.
 24. An image processing apparatus capable of reading imageson both sides of a document while transporting said document,comprising: a first image reading unit for reading an image on one sideof said document; a second image reading unit for reading an image onthe other side of said document; an image processing unit for processingthe image of the side read by said first and second image reading unit;a determining unit for determining which of the images of the sides readby the first and second image reading units is to be processed first bysaid image processing unit; and a selecting unit for allowing selectionabout which of the images of the sides read by said first and secondimage reading units is to be processed first, and said determining unitdetermines that the image of the side selected by said selecting unit isto be processed first.
 25. The image processing apparatus according toclaim 24, wherein said image processing unit performs image processingon a page-by-page basis.
 26. The image processing apparatus according toclaim 24, wherein said first image reading unit includes a CCD forreading an image on a front side of a document by emitting light to thefront side of said document and receiving reflected light from saiddocument.
 27. The image processing apparatus according to claim 24,wherein said second image reading unit includes a CIS for reading animage on a back side of a document by emitting light to the back side ofsaid document from a built-in light source and receiving reflected lightfrom said document.
 28. The image processing apparatus according toclaim 24, wherein said image processing unit performs image processingon a line-by-line basis in a page.
 29. An image processing method forreading images on both sides of a document while transporting saiddocument, and processing the read images, comprising the steps of:reading an image on one side of said document; reading an image on theother side of said document; determining which of the images of thesides is to be processed first; and processing the image of thedetermined side first, wherein it is determined that, of the read imageson both sides of said document, the image of the side that requires ashorter image processing time is to be processed first.
 30. The imageprocessing method according to claim 29, wherein image processing isperformed on a page-by-page basis.
 31. The image processing methodaccording to claim 29, wherein an image on one side of a document isread by a CCD for reading an image on a document by emitting light tothe document and receiving reflected light from the document.
 32. Theimage processing method according to claim 29, wherein an image on theother side of a document is read by a CIS for reading an image on adocument by emitting light to the document from a built-in light sourceand receiving reflected light from the document.
 33. The imageprocessing method according to claim 29, wherein image processing isperformed on a line-by-line basis in a page.